The term 'remote desktop' refers to a software application or an operating system feature that enables users to connect to a computer located in different area and use or run its own programs as if it were local. Controlling a desktop remotely is a kind of remote administration and is often used by enterprise help desks to provide technical support for their clients. Although remote administration is the primary use of remote desktop software, it can also be utilized for headless computers. Going headless means you can control two or more computers without having to attach PC peripherals such as mouse, monitor, and keyboard on each of them.

Remote desktop software can be found in most operating systems and platforms, and they are already supported in plenty of mobile devices such as the iPhone (see: Remote Control Your Linux Desktop Using the iPhone), Android and BlackBerry smartphones. Remote desktop connectivity depends upon any of a number of protocols such as Remote Desktop Protocol (RDP), Virtual Network Computing (VNC), Remote Frame Buffer Protocol, Apple Remote Desktop Protocol, and NX technology.

For those of you are interested, I have here a list of some of the best open-source remote desktop software (in no particular order) that you can download and use for free:

RealVNC (Free Edition)

RealVNC is platform-independent remote desktop software that has a server and client application for the Virtual Network Computing (VNC) protocol. It was created by some of the original VNC team members at AT&T. RealVNC is available in three editions: Free, Personal, Enterprise. The free and open source edition runs on different flavors of UNIX, and an updated and customized version of it is available in almost all Linux distributions. RealVNC relies on the RFB (remote framebuffer) protocol for connectivity.

Some of the latest features and enhancements of RealVNC (Free Edition):

Vinagre is a VNC client for the GNOME (included in GNOME 2.22) desktop environment. It has replaced xvnc4viewer as the default VNC client in the latest Ubuntu version. Vinagre has several unique and handy capabilities like allowing users to connect to multiple servers simultaneously and switch between them by tabs, VNC servers browsing and bookmarking. Although, it lacks other features existing in other VNC clients, like establishing an SSH tunnel, or controlling frame compression, color depth and frame rate. The user interface of Vinagre has already been translated into more than 40 different languages.

TightVNC

TightVNC is free and open-source remote desktop software that uses and improves VNC's RFB protocol. To enhance performance over low bandwidth connections, it applies 'tight encoding' of areas that is practically a combination of JPEG compression and other types of encoding. At a low frame rate, it is said that it's possible to watch videos and play DirectX games through TightVNC over a broadband connection.

Some of the main features of TightVNC:

* Scaling of the remote desktop* Automatic SSH tunneling* Full compatibility with the standard RFB protocol used in VNC* Enhanced web browser access* Support for two passwords, full-control and read-only

Grdc (GTK+/Gnome Remote Desktop Client)

Grdc (GTK+/Gnome Remote Desktop Client) is a GTK+ and GNOME-based remote desktop software that has the ability to connect to a VNC platform (using libvncserver0) as well as to Windows Terminal Servers (with rdesktop). Aside from the main program, a GNOME applet support for the client is available using the 'grdc-gnome' package.

Here are some other features of Grdc:

* Provides a list of remote desktop files for most frequently used servers* Ability to make quick connections by directly putting in the server name* Remote desktops with higher resolutions are scrollable/scalable in both window and fullscreen mode* Viewport fullscreen mode: remote desktop automatically scrolls when the mouse moves over the screen edge.* Floating toolbar in fullscreen mode, allows you to switch between modes, toggle keyboard grabbing, minimize, etc.

If you know of other excellent free and open-source remote desktop software for Linux that we fail to include above, feel free to share them with us via comment.